Give this a try.
lcRange=CHR(64+ColStart)+LTrim(Str(RowStart))+":"+CHR(64+ColEnd)+LTrim(Str(RowEnd)).  
If ColStart returns 3, CHR(64+ColStart) should return "C".

You might want to do this.

cStartingCell = CHR(64+ColStart)+LTrim(Str(RowStart))
cEndingCell   = CHR(64+ColEnd)+LTrim(Str(RowEnd))
lcRange       = cStartingCell+":"+cEndingCell

Makes your code self-documenting.

Tom Molloy